Process for recovering synthetic raw materials and fuel components from used or waste plastics

ABSTRACT

The invention concerns a process for recovering synthetic raw materials and fluid fuel components from used or waste plastics in accordance with patent application P 43 11 034,7. At least a partial flow of the depolymer produced according to this process is subjected, together with coal, to a coking process, fed to a thermal utilization system or introduced as a reducing agent into a blast furnace process. The depolymer can be used as an additive for bitumen and bituminous products.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This application is on 371 of PLT/EP95/03901 filed on Oct. 2, 1995.

The invention concerns a method to obtain chemical raw materials and/orliquid fuel components from old or waste plastics and the use of adepolymerization product formed according to this method, in which theold or waste plastics are depolymerized at an elevated temperature,perhaps with the addition of a liquid auxiliary phase, a solvent, or asolvent mixture, with the gaseous and condensable depolymerizationproducts (condensed product) and a sump phase (depolymerization product)formed, containing pumpable viscous depolymerization products, beingremoved in separate partial flows and with the condensed product anddepolymerization product being worked up, separately from one another.

2. Description of the Background

Such a method is described in German Patent No. A-4,311,034.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic embodiment of the present invention.

FIG. 2 illustrates a schematic similar to that of FIG. 1, except thatthe ascending sector is not formed by a pipe but rather a reactorsegment which is separated from the rest of the reactor contents by awall.

FIG. 3 illustrates a depolymerization unit of the present invention withtwo containers, which can be operated at different temperature levels.

FIG. 4 illustrates, as a section enlargement of FIG. 3, a T-shapedarrangement of the trap sector and branch.

FIG. 5 illustrates a process-technological alternative, in which aseparation device is connected directly downstream of the trap sector.

FIG. 6 provides a graphical representation of distillate content versusresident time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The products of the depolymerization are essentially subdivided intothree main product flows:

1) A depolymerization product in a quantity between 15 and 85 wt %,based on the plastic mixture used and which, depending on thecomposition and the individual requirements, can be subdivided intopartial product, flows conducted to the sump-phase hydrogenation,elevated-pressure gasification, low-temperature carbonization(pyrolysis), and/or other processes and uses.

They are mostly heavy hydrocarbons that boil around >480° C. and all ofwhich contain inert substances introduced into the process with the oldand waste plastics, such as aluminum films, pigments, fillers, and glassfibers.

2) A condensed product in a quantity of 10 to 80 wt %, preferably 20 to50 wt %, based on the plastic mixture used, which boils in a rangebetween 25° C. and 520° C. and can contain up to approximately 1000 ppmof organically bound chlorine.

The condensed product can be converted into a high-quality, syntheticraw oil (Syncrude), for example, by hydrotreating on stationarycommercial Co--Mo or Ni--Mo catalysts, or also can be directlyintroduced into chlorine-tolerating, chemical-technical, or commonrefinery methods as a hydrocarbon-containing base substance.

3) A gas in quantities of approximately 5 to 20 wt %, based on the usedplastic mixture, which in addition to methane, ethane, propane, andbutane can also contain gaseous hydrogen halides, such as mainlyhydrogen chloride and readily volatile, chlorine-containing hydrocarboncompounds.

The hydrogen chloride can be scrubbed out, for example, with water fromthe gas flow to obtain a 30% aqueous hydrochloric acid solution. Theresidual gas can be freed of organically bound chlorine throughhydrogenation in a sump-phase hydrogenation or in a hydrotreater and canbe conducted, for example, to the refinery gas processing.

The method parameters are thereby selected in such a way that as high aspossible a fraction of condensed product forms.

The individual product flows, in particular the condensed product, canbe subsequently used in the course of its further processing in thesense of a raw-material recycling--for example, as raw materials for theolefin production in ethylene units.

An advantage of the method is to be found in the fact that inorganicsecondary components of the old or waste plastics are concentrated inthe sump phase, whereas the condensed product not containing thesecomponents can be further processed in less expensive methods. Inparticular, the optimal adjustment of the processparameters--temperature and residence time--makes it possible to form,on the one hand, a relatively high fraction of condensed product and, onthe other hand, enables the viscous depolymerization product of the sumpphase to remain pumpable under the process conditions. The fact that anincrease in the temperature by 10° C., with an average residence time,increases the yield of products converted into the liquid phase by morethan 50% can serve as a useful approximation. FIG. 6 shows theresidence-time dependence for two typical temperatures.

The temperature range for the depolymerization preferred for the methodis 150° to 470° C. A range of 250° to 450° C. is particularly suitable.The residence time can be 0.1 to 20 h. A range of 1 to 10 h has provedto be sufficient, in general. The pressure is a less critical parameter.Thus, it may be absolutely preferable that the method be carried outunder reduced pressure--for example, if volatile components have to bewithdrawn because of reasons related to the method. However, relativelyhigh pressures are also practicable, but require a high apparatusoutlay. In general, the pressure should be 0.01 to 300 bar, inparticular 0.1 to 100 bar. The method can be advantageously carried outunder normal pressure or slightly above it, for example, up toapproximately 2 bar, which clearly reduces the apparatus outlay. Inorder to be able to degas the depolymerization product as completely aspossible and in order to increase the condensed product fraction evenmore, the method is advantageously carried out under slightly reducedpressure down to approximately 0.2 bar.

The depolymerization can be carried out in a common reactor, forexample, a stirred-vessel reactor, which is designed with theappropriate process parameters, such as pressure and temperature.Suitable reactors are described in the nonpublished German PatentApplications Nos. P 4,417,721.6 and P 4,428,355.5. Preferably, thereactor contents are moved via a circulation system connected to thereactor for protection against overheating. In a preferred specificembodiment, this circulation system comprises a furnace/heat exchangerand a highly efficient pump. The advantage of this method lies in thefact that a high circulation flow via the external furnace/heatexchanger makes it possible that, on the one hand, the necessarytemperature increase of the material in the circulation system remainssmall and, on the other hand, that favorable transmission conditions inthe furnace/heat exchanger result in moderate wall temperatures. In thisway, local overheating and thus uncontrolled decomposition and cokeformation are extensively avoided. The heating of the reactor contentstakes place in a manner that is very gentle by comparison.

A high circulation flow can be advantageously attained with highlyefficient rotary pumps. Like other sensitive elements of the circulationsystem, however, these have the disadvantage that they are susceptibleto erosion.

This can be counteracted in that the reactor contents withdrawn into thecirculation system, before their entry into the system, go through anascending sector integrated into the removal conduit, where coarsersolid particles with a correspondingly high sedimentation rate areseparated.

The reactor is designed in such a way that the removal device for thecirculation (circulation system) lies in an ascending sector for theessentially liquid reactor contents. By a suitable specification of theascending rate, essentially determined by the dimensioning of theascending sector and the dimensioning of the circulation flow, particleswith a higher sedimentation rate, which cause the erosion, can be keptfrom the circulation. The ascending sector within the reactor can bedesigned in the form of a tube, which is affixed essentially verticallyin the reactor (see FIG. 1).

Instead of a tube, the ascending sector can also be attained by having aseparation wall subdivide the reactor into segments (see FIG. 2).

The tube or the separation wall does not close off with the reactor lid,but projects beyond the full level. The tube or separation wall is sofar removed from the reactor bottom that the reactor contents are nothindered and can flow into the ascending sector without greatturbulence.

The solids are drawn off on the bottom of the reactor, together with thequantity of the depolymerization product, which is to be conducted to afurther processing. So that the sedimenting inert substances are removedas completely as possible from the reactor, the removal device for thedepolymerization product is preferably situated in the lower area, inparticular, on the bottom of the reactor.

In order to further support the most complete removal of the inertsubstances possible, the reactor is tapered downwards, preferably at thebottom, for example, tapering conically, or designed as an envelope of acone standing on its point.

FIG. 1 shows such a device in the sense of an exemplified embodiment.Old and waste plastic is introduced into reactor (1) from a supplycontainer (13) via a supply device (18) by means of a metering device(14) that closes in a gastight manner, for example, pneumatically. Abucket wheel sluice is very suitable, for example, as such a meteringdevice. The depolymerization product, together with the contained inertsubstances, can be removed via device (7) on the bottom of the reactor.The addition of the plastic, as well as the removal of thedepolymerization product, are advantageously carried out in a continuousmanner and are designed in such a way that a certain level (3) of thereactor contents is approximately maintained. The formed gases andcondensable products are removed from the head area of the reactor viadevice (4). The contents of the reactor are conducted to the gentleheating in the furnace/heat exchanger (6), using a pump (5), via aremoval conduit (16) to the circulation system, and via a feed conduit(17), recirculated into reactor (1). Tube (20), which forms an ascendingsector (2) for the reactor circulation flow, is situated in reactor (1).

The depolymerization product flow removed from the reactor is smallerthan the circulation flow by a factor of 10 to 40. This depolymerizationproduct flow is moved, for example, via a wet-grinding mill (9), so asto bring the inert components contained therein to a size admissible forfurther processing. The depolymerization product flow, however, can alsobe conducted via another separation device (8), where it is extensivelyfreed of the inert components. Suitable separation devices are, forexample, hydrocyclones or decanters. The inert components (11) can thenbe removed separately and, for example, supplied to a recycling.Alternatively, a part of the depolymerization product flow moved via thewet-grinding mill or via the separation device can be returned again tothe reactor, using a pump (10). The other part is conducted to therecycling, for example, sump-phase hydrogenation, low-temperaturecarbonization, or gasification (12). A part of the depolymerizationproduct can be removed directly from the circulation system via aconduit (15) and conducted to further processing.

FIG. 2 shows a reactor built similarly as in FIG. 1, with the differencethat the ascending sector is not formed by a pipe, but rather by areactor segment, which is separated from the rest of the reactorcontents by a separation wall (19).

When using old and waste! plastics from collections from households, theinert components (11) ejected via the separation device (8) consistmostly of aluminum, which, in this way, can be conducted to a materialrecycling. In addition, the ejection and recycling of aluminum open thepossibility of also completely utilizing composite packaging materials.The utilization can take place together with plastic packagingmaterials. This offers the advantage that a separation of thesepackaging materials can be omitted. Composite packaging materialsusually consist of paper or cardboard combined with a plastic and/oraluminum film. The plastic fraction is liquified in the reactor; thepaper and the cardboard are broken down into primary fibers, whichfollow the liquid because of their low sedimentation tendency. Thealuminum can be recovered to a large extent. Plastic and paper can besupplied to a raw-material utilization step after the depolymerizationhas been carried out.

FIG. 3 shows a depolymerization unit with two containers, which can beoperated at different temperature levels. The first depolymerizationcontainer (28) is, for example, equipped with a stirrer (33), so as tobe able to rapidly mix the old and waste plastics supplied via sluice(31) into the hot depolymerization product present. The seconddepolymerization container (1) downstream corresponds to the reactorfrom FIG. 1. The circulation to the gentle heating, essentiallyconsisting of pump (5) and furnace/heat exchanger (6), is therefore lowin solids. The depolymerization product, including the solid components,is removed at the bottom of the reactor. The quantitative solid/liquidratio in the removal device (7) of the container (1) can be between 1:1and 1:1000.

Preferably, the removal device (7) is a trap sector (21) with a branch(22), immediately downstream, placed essentially at right angles forthis purpose.

The trap sector (21) and branch (22) can be designed as a T-shaped tube.

The branch can also be equipped with mechanical separation aids (23).

A flow of organic components of the depolymerization product, which areessentially liquid under the existing conditions, is conducted away viathe branch (22). The depolymerization product arrives at the work-upunit via pump (27) or can also be returned to the reactor (1), at leastpartially, via conduit (32).

The quantity conducted away can be up to one thousand-fold that of thesluiced-out solids quantity. In the extreme case and perhapstemporarily, it is also possible that nothing will be conducted away viathe branch (22). By specifying the depolymerization quantity drawn offvia the branch (22), suitable flow ratios for the reliable discharge ofthe solids can be ensured. At the same time, the flow conducted awayshould be dimensioned in such a manner that solid particles are, ifpossible, not entrained to an appreciable extent. Preferably, the ratioof the sluiced-out solids quantity to the quantity conducted away is1:50 and 1:200.

The trap sector (21) or the trap tube is equipped with a sluice (24) atthe lower end in a special specific embodiment. A feed device (25) forflushing oil is installed above this sluice.

FIG. 5 shows a process-technological alternative, in which a separationdevice (26) is connected directly downstream to the trap sector (21).Preferably, a feed device (25) for flushing oil is installed on it.

Via the feed device (25), the flushing oil with a higher density thanthat of the depolymerization product is added in a quantity thatproduces a low flow rate of the liquid, then directed upwards within thetrap sector between the feed device (25) and the branch (22). This makesit possible for the trap sector (21) or the trap tube to always befilled with relatively fresh flushing oil below the branch (22). Aso-called stable layer with flushing oil is present in this part of thetrap sector (21). If nothing is conducted away via the branch (22), theflushing oil ascends in the trap sector (21) and finally arrives at thereactor (1).

Whereas, preferably, the main quantity of the organic components of thedepolymerization product is conducted away via the branch (22), themostly inorganic solid particles, which are contained in thedepolymerization product and which exhibit a sufficient sedimentationspeed, pass the part of the trap sector (21) filled with flushing oil.To this end, the organic depolymerization product components stilladhering to the solid particles are washed off or dissolved in theflushing oil.

The difference in the density between the depolymerization product andthe flushing oil should be at least 0.1 g/mL, preferably 0.3 to 0.4g/mL. The depolymerization product has a density of about 0.5 g/mL at atemperature of 400° C. As a suitable flushing oil, one can use, forexample, a vacuum gas oil with a density of approximately 0.8 g/mL,heated to approximately 100° C.

The length of the trap sector (21) filled with flushing oil isdimensioned in such a way that the solid particles on the lower end ofthe trap sector (21) are at least extensively free of adhering organicdepolymerization product components. It is also dependent on the type,composition, temperature, and the quantities of the depolymerizationproduct put through and the flushing oil used. The specialist candetermine the optimum length of the part of the trap sector (21) filledwith flushing oil by relatively simple experiments.

As shown in FIG. 3, the solid particles are discharged with a part ofthe flushing oil via the sluice (24). Sluice (24) is used for theseparation, according to the pressure, of the preceding and followingunit parts. A bucket wheel sluice is preferably used. However, othertypes of sluices, such as timed cycle sluices, are suitable for thispurpose. The discharged mixture has a solids content of approximately 40to 60 wt %.

Appropriately, another separation device (26) for the separation of theflushing oil and solid particles follows sluice (24)

Advantageously, a drag conveyor or a screw conveyor is used as theseparation device (26). They are directed upwards, at an incline, in theconveying direction. An angle to the horizontal plane of 30° to 60°, inparticular, approximately 45°, is preferred.

FIG. 5 shows another method variant. Here, the solid particles passthrough the separation device (26) immediately after passing the trapsector (21). A desired liquid level (34) is established in theseparation device (26) via a gas cushion, for example, consisting ofnitrogen, and the supply of flushing oil. The solid particles which, toa large extent, are freed of flushing oil are subsequently dischargedvia sluice (24), for example, a bucket wheel sluice or timed-cyclesluice.

A drainage screw (26), which can function as a suitable separationdevice, is schematically depicted in FIG. 3. A flushing oil with a lowerdensity, for example, a middle distillate oil, can be provided viaconduit (30). In this way, a heavier flushing oil is washed away fromthe solid particles. The low-viscous, light flushing oil can be at leastextensively separated from the solid particles in a simpler way andwithout great difficulties. The spent flushing oil can be conducted awayvia conduit (29), or at least partially introduced into thedepolymerization product conducted away via the branch (22). Theseparation device (26) preferentially works here under atmosphericconditions. The solid particles thus separated are discharged viaconduit (11) and can be supplied to a recycling unit.

If plastics from collections from households are used as old and wasteplastics, the solids discharged via conduit (11) consists mostly ofmetallic aluminum, which can be supplied to a subsequent materialutilization step.

FIG. 4 shows, as a section enlargement of FIG. 3, the T-shapedarrangement of the trap sector (21) and branch (22). Likewise,mechanical separating aids (23) and the flow conditions, drawn inschematically with arrows, are depicted.

The depolymerization product is easy to handle after separation from thegas and condensed product, since it remains readily pumpable above 200°C. and in this form represents a good charge stock for the subsequentprocess stages and other utilization purposes.

The depolymerization product can, however, also be brought tosolidification by means of a so-called cooling conveyor and thus can beturned into a solid form. For example, endless belts made of stainlesssteel are suitable. As a rule, they run by pull-over cylindrical guidedrums or guide disks. The product can be supplied as a film in the frontof the cooling conveyor, for example, by means of a broad-band nozzle.The lower side of the cooling conveyor is sprayed with a cooling liquid,wherein the product, however, is not wetted. By cooling the conveyor,the product on it also undergoes a lowering of the temperature andsolidifies. In addition to the cooling from below, the depolymerizationproduct can also be cooled from above by a supply of air. The solid filmformed can be broken at the end of the cooling conveyor, for example, bymeans of a routing-crushing roller or by means of a grid-crushingroller. For the subsequent work-up or storage, it has also provedconvenient if the fragments are not larger than the palm of a hand.Perhaps, the fragments can also be further comminuted, for example,ground.

The depolymerization product can be introduced, in pumpable form,directly into the subsequent process stages or can be supplied for otherutilization purposes. If an intermediate storage is necessary, it shouldbe done in tanks in which the depolymerization product is maintained attemperatures at which it can be easily pumped, generally at above 200°C. If a longer storage is desired, one possibility is to store thedepolymerization product in solid form. In broken form, thedepolymerization product can be transported, stored, and supplied tosubsequent processes and utilizations analogous to the fossilfuel--mineral coal.

The invention under consideration concerns a method according to claims1, 3, and 5, and concerns uses according to claims 7 and 8. Preferably,a depolymerization product is used, which is at least extensively freeof coarse inorganic solid particles, in particular aluminum metal.

In the method of the invention according to claim 1, at least onepartial flow of the depolymerization product, together with coal, issubjected to a coking. Not all types of coal are suited for theproduction of high-quality coke. Such a coke, for example, blast-furnacecoke, should consist, as much as possible, of coarse pieces and shouldnot be very pulverizable. It must have a minimum strength, so that asufficient bed in a blast furnace can be attained, without the cokedecomposing under the weight of the bed and, as a consequence, the blastfurnace becoming clogged. Suitable types of coal are, for example, thecaking fat coal of the Ruhr area or gas coal. Such caking coals areavailable in limited quantities and are more expensive, for example,than boiler coal.

Surprisingly, it was discovered that poorly caking coals form a cakeduring the coking process, if the depolymerization product is added tothem. During the high-temperature coking process, which usually takesplace at 900° to approximately 1400° C., with the exclusion of air,coking products with binder characteristics and which bring about acaking of the coal are apparently formed from the introduceddepolymerization product. Something analogous is true also for thecoking of brown coal for the production of semicoke, for example, in theopen-hearth process. The desired effect of the caking is attained if thedepolymerization product and coal are used in the ratio of 1:200 to1:10. A range of 1:50 to 1:20 has proved to be particularly favorable.

In the method of the invention according to claim 3, at least onepartial flow of the depolymerization product is subjected to a thermalutilization. "Thermal utilization" is understood to mean the oxidationof a substrate, utilizing the heat of reaction thereby formed. On thebasis of its high energy content and its relatively low chlorinecontent, in comparison to old or waste plastics, with a simultaneouslyhigh homogeneity, the depolymerization product is a suitable fuel foruse in power plants of all types and in cement plants. Thedepolymerization product can thereby be sprayed in as a liquid attemperatures above 200° C. via lances, for example, as a substitute forheavy heating oil, or can be introduced in solid form, for example,broken or ground.

In the method of the invention according to claim 5, at least onepartial flow of the depolymerization product is used as a reducing agentin a blast furnace process. The depolymerization product can also beutilized here as a substitute for heavy heating oils, which are normallyused for this purpose. Here, as in the thermal utilization, a relativelylow content of chlorine of the depolymerization product of less than 0.5wt % proves to be a particular advantage.

The depolymerization product can therefore be advantageously used as abinding additive in the coking of coal, as a reducing agent in blastfurnace processes, and as fuel in furnaces, power plants, and cementplants.

Moreover, the depolymerization product can be used as a an additive tobitumen and bituminous products. Polymer-modified bitumens are used inmany areas of the construction industry, especially in roof-sealingmaterials and in road construction. The characteristics of the bitumen,such as toughness, tensile strength, and wear capacity, are improved bythe polymers contained in the depolymerization product. Thedepolymerization product undergoes chemical bonding during the jointheating with bitumen and bitumen derivatives because of its residualactivity. This is, in part, the cause of the aforementioned and desiredcharacteristic improvements.

By means of this modification, the cold flexibility as well as thestability of the bituminous material can be improved. An improvement ofthe elastic characteristics of the bitumen and the adhesion capacity onmineral filler material can also be attained by admixing polymers. Thechemical reaction with bitumen has, moreover, the advantage that, forexample, in hot storage, no segregation can take place or it is verylimited. The residual activity of the depolymerization product can beenhanced by the introduction of functional groups, for example,according to the method of European Patent Applications Nos. 0,327,698,0,436,803, and 0,537,638. Optionally, the bitumens or the bituminousproducts thus modified can also contain crosslinking agents (seeEuropean Patent No. 0,537,638 Al).

An addition of 1 to 20 parts by weight of the depolymerization productper 100 parts by weight of bitumen has proved to be practicable. Anaddition of 5 to 15 parts by weight of the depolymerization product per100 parts by weight of bitumen is particularly favorable.

EXAMPLE 1

Depolymerization of old plastics

In a stirred-vessel reactor with a content of 80 m³, provided with acirculation system having a capacity of 150 m³ /h, 5 t/h of mixedagglomerated plastic particles with an average particle diameter of 8 mmare pneumatically introduced. The mixed plastic is material that comesfrom the Dual System German (DSD) collection from households andtypically contains 8% PVC.

The plastic mixture is depolymerized in a reactor at temperaturesbetween 360° C. and 420°.

Four fractions are thereby formed; their quantitative distribution issummarized in the following table as a function of the reactortemperature.

    ______________________________________                                               I        II          III       IV                                      T      Gas      Condensed   Depolymerization                                                                        HCI                                      °C.!                                                                          wt. %!  Product  wt. %!                                                                           Product wt. %!                                                                           wt. %!                                 ______________________________________                                        360    4        13          81        2                                       380    8        27          62        3                                       400    11       39          46        4                                       420    13       47          36        4                                       ______________________________________                                    

The depolymerization product flow (III) is continuously removed. Theviscosity of the depolymerization product is 200 mpas at 175° C.

EXAMPLE 2

The depolymerization product from the processing of waste plastics fromDSD collections from households according to Example 1 is admixed withcoking coal in various quantitative ratios. The mixtures are coked in anexperimental coking furnace.

Cokes are obtained with the characteristics described below:

    ______________________________________                                        Experiment No.   1      2        3    4                                       ______________________________________                                        Coal/Depolymerization                                                         Ratio            100:0  99:1     98:2 95:5                                    CRI Index        29     28       27   27                                      CSR Index        59     61       62   63                                      Coke Strength M 40 (in %)                                                                      73     76       77   78                                      Coke Wear M 10 (in %)                                                                           8      7        6    5                                      ______________________________________                                    

The values show that the addition of depolymerization product improvesthe coke strength (M 40) and reduces the wear tendency (M 10).Furthermore, the gasification reactivity (CRI index) is reduced,accompanied by an improved coke strength after gasification (CRI index)with the addition of depolymerization agent.

CRI: Coke Reaction Index

CSR: Coke Strength after Reaction Index

M 40: MICUM test 40

M 10: MICUM test 10

We claim:
 1. A method for producing chemical raw materials and liquidfuel components from old or waste plastics, which comprises:a)depolymerizing the old or waste plastics at an elevated temperature,optionally with the addition of a liquid auxiliary phase, a solvent, ora solvent mixture, thereby forming gaseous and condensabledepolymerization products (condensed product) and a pumpable, viscoussump phase (depolymerization product); and b) removing said gaseous andcondensable depolymerization products (condensed product) and saidpumpable viscous sump phase (depolymerization product) in separatepartial flows with the condensed product and depolymerization productbeing worked up, separately from one another;wherein at least onepartial flow of the depolymerization product is supplied to coal to becoked in order to provide an improved caking during coking.
 2. Themethod of claim 1, wherein the depolymerization product and the coal arepresent in a ratio of about 1:200 to 1:10.
 3. The method of claim 2,wherein said ratio is from about 1:50 to 1:20.
 4. The method of claim 1,wherein at least one other said partial flow of the depolymerizationproduct is subjected to oxidation.
 5. The method of claim 4, wherein theoxidation of the depolymerization product is effected in a power plantor a cement plant.
 6. The method of claim 1, wherein at least one othersaid partial flow of the depolymerization product is used as a reducingagent in a blast furnace process.
 7. The method of claim 1, wherein thedepolymerization product is used as a pumpable mass with a temperatureabove about 200° C. or as a solid.
 8. The method of claim 1, whereinsaid elevated temperature is from about 150° to 470° C.
 9. The method ofclaim 7, wherein said elevated temperature is from about 250° C. to 450°C.
 10. The method of claim 1, which is effected at a pressure of fromabout 0.01 to 300 bar.
 11. The method of claim 1, wherein a pressure ofup to about 2 bar is used.
 12. The method of claim 8, wherein thedepolymerization product is ground or broken after cooling.
 13. A methodof fueling a furnace, power plant or cement plant, which comprisescombusting a partial flow of the depolymerization product of claim 1.14. A method of reducing raw materials in a blast furnace, whichcomprises adding a partial flow of the depolymerization product of claim1 to said raw materials in said blast furnace.
 15. A method of bindingcoal during coking thereof, which comprising adding the depolymerizationproduct of claim 1 to said coal during coking, and then subjecting saidand depolymerization product to said coking.
 16. A method of enrichingbitumen or a bituminous products or both, which comprises adding apartial flow of the depolymerization product of claim 1 to said bitumenor said bituminous product.
 17. The method of claim 16, which comprisesadding about 1 to 20 parts by weight of depolymerization product perabout 100 parts by weight of bitumen.
 18. The method of claim 17,wherein about 5 to 15 parts by weight of the depolymerization product isadded per about 100 parts by weight of bitumen.